1. Field of the Invention
The invention in general relates to transducers and particularly to a transducer for providing an omnidirectional beam pattern in one plane.
2. Description of the Prior Art
A variety of transducer arrangements exist for providing an omnidirectional beam pattern in one plane and a line radiation pattern in planes normal to the omnidirection pattern. When employing large cylindrical piezoceramic tubes or cylinders that have been poled radially and operated in the thickness mode, omnidirectional patterns have been produced which are highly unsatisfactory. This may be due to the fact that when operated in a thickness plate mode or cylinder thickness mode higher overtones of various low frequency modes along with various cylindrical modes can be and are excited.
In order to eliminate unwanted modes in flat plate or wedge-shaped piezocermics resort is made to slicing and/or dicing the piezoceramic which has the effect of altering the complex mode structure and essentially completely eliminating the undesirable effects of the extraneous vibrational modes. When a piezoceramic cylinder is diced it alters the surface thereof so as to present a multitude of isolated elements or posts. In the thickness mode of operation electrical contact must be made to the inner and outer surface of the cylinder which means that adequate electrical contact must be made to all of the upstanding posts which can, for various designs, require several thousand electrode connections. Attempts to wrap a conducting foil or screen around the outside of the diced cylinder have proved unsatisfactory.